This invention relates to water absorbent articles made from crosslinked polyelectrolytes, methods for their preparation, and to a composition containing polyelectrolytes and monomeric amine/epihalohydrin adducts which is useful to make absorbent articles.
It is known from U.S. Pat. Nos. 3,669,103 and 3,670,731 that crosslinked polymeric sorbents can be sandwiched between flexible supports to achieve disposable diapers or dressings.
It is further known from U.S. Pat. Nos. 2,988,539; 3,393,168; 3,514,419, and 3,557,067 that water swellable crosslinked carboxylic copolymers can be prepared. However, these prior art copolymers are all crosslinked during copolymerization or crosslinked after polymerization with subsequent neutralization of the carboxylic acid groups to form water absorbent polyelectrolytes and hence these prior art polyelectrolytes cannot be crosslinked in-situ as an absorbent coating on a substrate or as a flexible film thereof.
The use of epihalohydrins to cure polyelectrolytes is disclosed in U.S. Pat. No. 3,980,663. However, these crosslinkers are inefficient, requiring up to 10% by weight of the epihalohydrins to obtain a suitable product.
The patent by N. D. Burkholder, U.S. Pat. No. 4,076,673 dated Feb. 28, 1978, discloses methods of curing polyelectrolytes to water absorbent articles wherein the curing or crosslinking agent is a polyamidepolyamine epichlorohydrin adduct such as Polycup.RTM. 172 made by Hercules, Incorporated.